Many modern vehicles include on-board electronic control systems that manage, measure, and report operation of the vehicle's various subsystems. On-board electronic control systems may include or otherwise support on-board diagnostic (OBD) services that enable vehicle owners and repair technicians to access diagnostic information or other forms of operational information from the control system. As one example, on-board electronic control systems of a vehicle may be accessed via a data interface in the form of a physical wired data link connector or data port. OBD information may be communicated over this data interface using a variety of protocols, including ALDL, OBD-I, OBD-1.5, OBD-II, etc.